Synthetic studies towards the diterpene natural product FCRR toxin have been undertaken. Ail intermolecular [5+2] oxidopyrylium-alkene cycloaddition reaction was employed to construct the 7-5-6 tricyclic framework. The reaction proceeded with very high regio- and stereoselectivity and the bridging ether was reductively cleaved to unmask the carbocycle. (C) 2003